[PATCH v6] Bluetooth: qca: Fix delayed hw_error handling due to missing wakeup during SSR

[Shuai Zhang]

When Bluetooth controller encounters a coredump, it triggers
the Subsystem Restart (SSR) mechanism. The controller first
reports the coredump data, and once the data upload is complete,
it sends a hw_error event. The host relies on this event to
proceed with subsequent recovery actions.

If the host has not finished processing the coredump data
when the hw_error event is received,
it sets a timer to wait until either the data processing is complete
or the timeout expires before handling the event.

The current implementation lacks a wakeup trigger. As a result,
even if the coredump data has already been processed, the host
continues to wait until the timer expires, causing unnecessary
delays in handling the hw_error event.

To fix this issue, adds a `wake_up_bit()` call after the host finishes
processing the coredump data. This ensures that the waiting thread is
promptly notified and can proceed to handle the hw_error event without
waiting for the timeout.

Test case:
- Trigger controller coredump using the command: `hcitool cmd 0x3f 0c 26`.
- Use `btmon` to capture HCI logs.
- Observe the time interval between receiving the hw_error event
and the execution of the power-off sequence in the HCI log.

Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@xxxxxxxxxxxxxxxx>
Signed-off-by: Shuai Zhang <shuai.zhang@xxxxxxxxxxxxxxxx>
---
Changes v6:
- Replace wake_up_bit with clear_and_wake_up_bit 
- Link to v5
  https://lore.kernel.org/all/20260409112233.3326467-1-shuai.zhang@xxxxxxxxxxxxxxxx/

Changes v5:
- Replace clear_and_wake_up_bit with wake_up_bit
- Link to v4
  https://lore.kernel.org/all/20260327083258.1398450-1-shuai.zhang@xxxxxxxxxxxxxxxx/

Changes v4:
- add Acked-by signoff
- Link to v3
  https://lore.kernel.org/all/20251107033924.3707495-1-quic_shuaz@xxxxxxxxxxx/

Changes v3:
- add Fixes tag
- Link to v2
  https://lore.kernel.org/all/20251106140103.1406081-1-quic_shuaz@xxxxxxxxxxx/

Changes v2:
- Split timeout conversion into a separate patch.
- Clarified commit messages and added test case description.
- Link to v1
  https://lore.kernel.org/all/20251104112601.2670019-1-quic_shuaz@xxxxxxxxxxx/
---
 drivers/bluetooth/hci_qca.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/bluetooth/hci_qca.c b/drivers/bluetooth/hci_qca.c
index c17a462ae..228a754a9 100644
--- a/drivers/bluetooth/hci_qca.c
+++ b/drivers/bluetooth/hci_qca.c
@@ -1108,7 +1108,7 @@ static void qca_controller_memdump(struct work_struct *work)
 				qca->qca_memdump = NULL;
 				qca->memdump_state = QCA_MEMDUMP_COLLECTED;
 				cancel_delayed_work(&qca->ctrl_memdump_timeout);
-				clear_bit(QCA_MEMDUMP_COLLECTION, &qca->flags);
+				clear_and_wake_up_bit(QCA_MEMDUMP_COLLECTION, &qca->flags);
 				clear_bit(QCA_IBS_DISABLED, &qca->flags);
 				mutex_unlock(&qca->hci_memdump_lock);
 				return;
@@ -1186,7 +1186,7 @@ static void qca_controller_memdump(struct work_struct *work)
 			kfree(qca->qca_memdump);
 			qca->qca_memdump = NULL;
 			qca->memdump_state = QCA_MEMDUMP_COLLECTED;
-			clear_bit(QCA_MEMDUMP_COLLECTION, &qca->flags);
+			clear_and_wake_up_bit(QCA_MEMDUMP_COLLECTION, &qca->flags);
 		}
 
 		mutex_unlock(&qca->hci_memdump_lock);
-- 
2.34.1